When connected to a UP2715k display using a single DisplayPort connection (1xDP) system cannot show 4k2k resolution and when connected to monitor with Dual DisplayPort connections (2xDP) is detected as 2 separate monitors instead of showing 5k3k."

Workaround: The MacPRo ME253TA/A does not support Extended display identification data (EDID) with DisplayID tile display. If you connect a single DisplayPort (1xDP) connection to the monitor Mini-DisplayPort input (mDP) you can display 4k2k (max resolution).

Apple MacPro (2013, Cylinder) with 10.9.5

If you connect a Apple MacPro a UP2715k display using the mDP input, the shows black screen.